Conventionally, a plasma processing apparatus has been used in various fields. Patent Document 1 describes a plasma etching apparatus using parallel plates for generating plasma.
Recently, there has been developed a plasma etching apparatus using a radial line slot antenna for generating plasma (Patent Document 2). In the plasma processing apparatus using the radial line slot antenna, a slot antenna having a multiple number of slots is disposed on a dielectric window of a processing chamber. Microwave radiated through the multiple number of slots of the slot antenna is introduced into the processing chamber through the dielectric window made of a dielectric material. A processing gas is excited into plasma by the energy of the microwave.
In the microwave plasma generated by the radial line slot antenna, plasma having a relatively high electron temperature of several eV is diffused in a region (here, referred to as a plasma exciting region) directly under the dielectric window and the electron temperature of the plasma becomes to be as low as, e.g., about 1 eV to about 2 eV in a region (referred to as a plasma diffusing region) directly above a substrate and equal to or larger than about 100 mm below the dielectric window. That is, the distribution of the electron temperature of the plasma is defined as a function of a distance from the dielectric window.
In the plasma etching apparatus of the radial line slot antenna type, an etching gas is supplied into the low electron temperature region, and dissociation of the etching gas (i.e., a generation amount of etching species in the plasma) is controlled. As a result, an etching reaction (a surface chemical reaction of the substrate according to the etching species) is controlled. Accordingly, etching can be performed with high accuracy and damage on the substrate can be reduced greatly. By way of example, it is possible to fabricate a device accurately with designed dimensions in an etching process for forming a spacer, and, further, damage generation, such as a recess, on the substrate can be suppressed.
Patent Document 1: Japanese Patent Laid-open Publication No. 2008-047687
Patent Document 2: Japanese Patent Document Laid-open Publication No. 2010-118549
However, with the scale-up of a substrate to be processed, there has been a demand for improving uniformity of a substrate surface processing amount in the surface of the substrate. For example, in the etching apparatus using the radial line slot antenna described in Patent Document 2, it is difficult to uniformize an etching rate and an etching shape in the surface of the substrate. That is, it is required to perform the etching process uniformly on the surface of the substrate.